On the background of the relevant technical field, there is Japanese Patent Application Laid-Open No. 2005-246692 (hereinafter, referred to as Patent Literature 1), in which there is disclosure that upon plastics being laser-welded, laser beam scan on the weld line is performed at the junctions two times or more and the laser beam scan on such weld line may well be performed on different peripheries.
In Japanese Patent Application Laid-Open. No. 2005-246913 (hereinafter referred to as Patent Literature 2), there is disclosure that resins are preliminarily welded to each other with two laser beams respectively scanned on two weld lines spaced apart from each other with a predetermined interval between them; and the resins are welded to each other in the end with the intermediary between those two weld lines welded.
In Japanese Patent Application Laid-Open No. 2006-73296 (hereinafter referred to as Patent Literature 3), there is disclosure on the laser-welded structure between a housing and a lens which is provided with the first welded section where the whole circumference of the housing and the lens respectively is laser-welded and the second welded section where the whole circumference of them respectively is laser-welded at the outer circumference of the first welded section and on the laser welding method thereof.
In Japanese Patent Application Laid-Open No. 2010-162587 (hereinafter referred to as Patent Literature 4), there is disclosure with regard to electronic equipment and flow meters that upon the other components besides their circuit substrates and so forth being fixed in position with thermal welding methods including laser welding method in use, an insulating section is provided on a channel holding body in order to restrain their circuit substrates and so forth from being thermally affected.
In Japanese Patent Application Laid-Open No. 2010-201695 (hereinafter referred to as Patent Literature 5), there is disclosure on the laser welding method comprising the steps of preliminarily forming a welded section with the resins overlapped with each other; and irradiating again laser beam onto the vicinity of such welded section so as to make the resins attached with each other, thereby the resins being welded to each other in the end.